Feed and backlash mechanism



Dec. 16, 1 958 A. J. JONES FEED AND BACKLASH MECHANISM Filed Feb. 2, 1956 3 Sheets-Sheet 1 ALVIN J. JONES ATTORNEY Dec. 16, 1958 A. J. JONES FEED AND BACKLASH MECHANISM Filed Feb. 2, 1956 3 Sheets-Sheet 2 y w Q V Dec. 16, 1958 A. J. JONES 2,364,207

FEED AND BACKLASH MECHANISM Filed Feb. 2, 1956 5 Sheets-Sheet 3 N l O l 3 a INVENTOR ALVIN J. JONES ATTORNEY United States Patent-O FEED AND BACKLASH MECHANISM Alvin J. Jones, Waynesboro, Pm, assignor to Landis Tool Company, Waynesboro, Pa.

Application February 2, 1956, Serial No. 563,025

4 Cl ims! 51-1 This invention relates to feed mechanisms for machine tools particularly grinding. machines.

It is an object of this machine to provide means for eliminating backlash in the connections between the driving means and all other elements of a feed mechanism.

Another object is to provide means for indicating movement of the grindingwheel as it approaches a predetermined position.

Another object is to provide contacting surface of cooperating parts which will penetrate any lubricant film present on said surfaces.

Figure 1 is at end elevation of a grinding wheel support partly in section.

Figure 2 is a partial front elevation in section.

Figure 3 is a plan view cut away to show the relation between the various parts.

Figure 4 is a sectional plan view of the feed mechanism.

Numeral indicates a slide base normally mounted on a machine base (not shown). 11 is a wheel base slidably mounted on base 10 having a grinding wheel 12 rotatably mounted thereon. Manual adjustment of base 11 on slide 10 may be effected by means of a hand wheel connected through gearing to a vertical shaft 21 extending downwardly to wheel support 11. The lower end of said vertical shaft is in the form of a pinion 25 meshing with two racks 26 and 27 slidably mounted in slide member 10. Rack 26 is connected to a piston 28 in cylinder 30. This connection and the means for controlling the feed movement of the rack 26 is substantially the same as that shown in co-pending application, S. N. 530,465 filed August 25, 1955.

At the front end of rack 27 is a piston slidably mounted in a cylindrical bore 36. Fluid under pressure from a pump is supplied through a line 41 and a regulating valve 42 through line 43 to said cylinder 36 to provide a constant pressure urging said rack to the right and thereby tending to rotate pinion 25 to eliminate backlash between said pinion and rack 26.

The means for indicating the approach of the grinding wheel 12 to a predetermined position consists of an indicator mounted on a housing 51 which encloses a hand wheel shaft (not shown) which is attached to hand wheel 20. A vertical operating rod 52 extends downwardly through a bore 53 in vertical shaft 21. Said rod rests on a bar supported for oscillation at spaced points 61 and 62 by bell cranks 63 and 64. Said bell cranks are pivotally supported in base member 10 at points 65 and 66. Vertical arms 67 and 68 of said bell cranks are attached to a horizontal shaft 69 which engages the end of a sliding pin 70 in base member 10. The other end of said pin engages an arm 71 movable with rack 27. Indicator 50 shows the position of the wheel for feeding or resetting and is operable in response to the feed piston 28.

The means for providing a slow grinding feed includes a pin in rod 26 which serves to engage a member 81 2,864,207 Patented Deg. .1958

pivoted at 82 Said member 81 is located so that it is engaged by said pin near the end of the rapid feed movement of piston 28. The end of said member opposite the pivot is connected by a link 85 to the stem 86 of a cushioning valve 87. Said valve is actuated to cushion the movement of said pivoted member 81 as it engages roller 90 resiliently supported on flexible member 91 in piston rod 92. Said piston rod is connected to piston 93 in cylinder 94. A limit switch for indicating the end of the slow feed is mounted at the end of said cylinder to be actuated by a pin 101 slidably mounted in the head 95 of cylinder 94 and adapted to be actuated by piston 93.

Member 81 urges roller 90 against a feed control memher which is pivotally mounted at 111. The member 110 may be adjusted about pivot 111 by any suitable means to adjust the inclination of its surface 112 along which roller 90 is drawn to control the rate of move; ment of feed piston 28.

Operation The operation of the feed mechanism by piston 28 in cylinder 30 and controlled by roller 90 drawn along cam surface 112 by piston 93 is described in detail in said copending application S. N. 530,465.

Feed rack 26 which is moved axially by piston 28 has rack teeth in engagement with the teeth of gear 25. Since the vertical shaft 21 on which the gear is formed may be rotated only by the hand wheel 20, said shaft does not turn in response to the movement of feed rack 26 and the entire wheel support 11 is moved along with said feed rack. Fluid under pressure supplied by pump 40 to cylinder 36 urges piston 35 and rack 27 to the right in Figure 4. The teeth of rack 27 also engage with gear 25. Thus, during a feeding movement, the teeth of rack 26 engage one side of gear teeth 25 while the teeth of rack 27 engage the opposite sides of the teeth in said gear 25 thus eliminating all backlash. With the backlash eliminated, both racks move in the same direction.

Arm 71 attached to rack 27 engages the end of pin 70 slidably mounted in base member 10, the other end of said pin engages horizontal shaft 69 to move it forward in unison with said rack, wheelbase 11 and grinding wheel 12. Since shaft 69 is attached to the arms of spaced beil cranks 63 and 64, the bar 60, which is supported by the other arms of the bell cranks 63 and 64, is moved upwardly by the rocking of said bell cranks at the same time the shaft 69 moves forward.

The vertical operating rod 52 resting on the bar 60 is moved upwardly. The upper end of said rod engages and actuates indicator 50 to show the extent of upward movement of said rod and bar 60. Said indicator shows the movement in terms of increments of movement of wheelbase 11 and grinding wheel 12.

I claim:

1. A feed mechanism for a grinding machine including a base member, a grinding wheel support slidably mounted on said base member, a grinding wheel rotatably mounted on said support, means for effecting movement of said wheel support on said base member including a sliding rack and means for actuating said rack, connections between said rack and said wheel support including a manually operated shaft having a pinion gear thereon engaging the teeth of said rack for manual adjustment of said wheel support relative to said rack and means for taking up the backlash between said pinion and said rack comprising a second rack also in engagement with said pinion and slidably mounted in said base parallel to said first rack, said second rack having a piston on one end, means for applying fluid under pressure to said piston whereby to urge said pinion in a direction opposite to that in which it is urged by said first mentioned rack.

2. A feed mechanism for a grinding machine including a base member, a grinding wheel support slidably mounted on said base member, a grinding wheel rotatably mounted on said support, means for effecting movement 'of said wheel support on' said base member including a sliding rack and means for actuating said rack, connections between said rack and said wheel support including amanually operated shaft having a pinion gear thereon engaging the teeth of said rack for manual adjustment of said wheel support relative to said rack and means for taking up the backlash between said pinion and said rack comprising a second rack slidably mounted in said baseand parallel to said first rack, said second rack having a piston on one end, means for applying fluid under pressure to said piston whereby to urge said pinion in a direction opposite to that in which it is urged by said first mentioned rack, a feed indicator comprising a rod movable along said rack and means to convert hori- 'zontal movement of said rod to vertical movement comprising a pair of bell cranks attached to said rod at longitudinally spaced points thereon, the other end of each of said bell cranks being attached to a bar for raising and lowering same, a dial indicator and a connection between said bar and said dial indicator.

3. A feed mechanism for a grinding machine including a base member, a grinding wheel support slidably mounted on said base member, a grinding wheel rotatably mounted on said support, means for efiecting movement of said wheel support on said base member including a 2,884,201 T t. a

sliding rack and means for actuating said rack, connections between said rack and said wheel support including a manually operated shaft having a pinion gear thereon engaging the teeth of said rack for manual adjustment of said wheel support relative to said rack and means for taking up the backlash between said pinion and said rack comprising a second rack also in engagement with said pinion and slidably mounted in said base parallel to said first rack, fluid pressure means for actuating said second rack in a direction opposite to that of said first rack whereby to eliminate backlash between said pinion and said first rack.

4. In a grinding machine, a grinding wheel support, a

References Cited in the file of this patent UNITED STATES PATENTS Player et al Feb. 2, 1932 Muskovin Apr. 8, 1941 

